S
saxondale
Why not check the voltage with it connected and disconnected? About 0v with it connected and open circuit voltage with it disconnected or operated? This would have pointed towards the wiring as opposed to the panel.
just that - experiance again says its the cable (especially as the op said about reflooring - its a standard question to ask about works been done recently) so you check that before the panel
but in this case (though I would have to mock one up first ) I think you`ll either get 13v either way or no change from the expected figures even with the fault
if the cct cable meters out correctly then I would be thinking the reason its not triggering the panel could be because theres a short between 13v or 0v and the alarm cores so even though the relay opens the panel still see`s 13v (or 0v if its on the negative legs) at the return terminal